We report the photoionization studies of cesium from the 6$p$ ${}^2{P}_{3/2}$ excited state to measure the photoionization cross section at and above the first ionization threshold, oscillator strength of the highly excited transitions, and extension in the Rydberg series. The photoionization cross section at the first ionization threshold is measured as 25 (4) Mb and at excess energies 0.02, 0.04, 0.07, and 0.09 eV as 21, 19, 17, and 16 Mb, respectively. Oscillator strength of the 6$p$ ${}^2{P}_{3/2}$ $\to$ $nd$ ${}^2{D}_{5/2}$ (23 $⩽$ $n$ $⩽$ 60) Rydberg transitions has been extracted utilizing the threshold value of photoionization cross section and the recorded $nd$ ${}^2{D}_{5/2}$ photoionization spectra.

• Received 12 May 2010

DOI:https://doi.org/10.1103/PhysRevA.81.063432